T2: Snappi Based Route Convergence Test Changes

[deepak-singhal0408]

Description of PR

Summary:
T2 Snappi based automation testcases, currently didnt have Different types of upstream neighbors support.
As part of this PR,

1. Different upstream neighbors support is added.
2. Fixed a bug where t2_uplink_fanout_info was not parsed correctly.
3. Po members flap test to skip if num_po_members < 2.

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

T2 Snappi based automation testcases, currently didnt have Different types of upstream neighbors support.

How did you do it?

Different upstream neighbors support is added. This also covers different route policies on different types of upstream neighbors

How did you verify/test it?

Ran the testcases locally and captured the results.

Any platform specific information?

NA

Supported testbed topology if it's a new test case?

Documentation

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[deepak-singhal0408]

MSFT ADO:30659116